Compositions and method for wastewater treatment

ABSTRACT

Compositions, systems, and methods of using alkaline-producing Aluminate salts in the sludge collection and digestion steps of wastewater processing to reduce acidity and/or build alkalinity, reduce hydrogen sulfide release, and reduce phosphate in the effluent.

RELATED APPLICATIONS

This application incorporates by reference in its entirety and claimspriority to U.S. Provisional Application No. 62/572,664, filed Oct. 16,2017.

This application incorporates by reference in its entirety and claimspriority to U.S. Provisional Application No. 62/615,391, filed Jan. 8,2018.

FIELD OF THE INVENTION

This invention relates generally to wastewater treatment and, morespecifically, to reduction of odor and corrosion that can occur in awastewater anaerobic digestion process.

BACKGROUND OF THE INVENTION

Modern wastewater treatment is a foundational element of nearly everycommunity. In many facilities, the bulk of the focus has been on thetreatment of raw sewage that enters and exits the facility, commonlyknown as water and wastewater streams. This process also creates a sideproduct, known as sludge. This sludge is separated from the main watertreatment line, and thereafter treated separately. Unfortunately, thissludge can be significantly malodorous.

In many wastewater plants, sludge captured from the bottom of theprimary clarifier and secondary clarifier is combined and fed into ananaerobic digester. Anaerobic digestion uses microorganisms to breakdownthe wastewater sludge in the absence of oxygen to reduce sludge volume.

Under anaerobic conditions, bacteria still require elemental oxygen fortheir metabolic functions. One primary chemical that is ubiquitous inwater and wastewater streams is the sulfate ion (SO42-). Certainanaerobic bacteria have sulfate reducing activity that, in essence,strip the oxygen-atoms from SO42-, resulting in the formation ofhydrogen sulfide (H2S). H2S is a malodorous acidic gas that causescorrosion.

There is a long list of chemicals that are well known in the wastewatertreatment industry as acceptable additives for the purpose of oxidizingor scavenging hydrogen sulfide, these include, for example, chlorine,bleach, hydrogen peroxide, ozone, potassium permanganate, ferricchloride, ferrous sulfate, sodium hydroxide, Quinone compounds, andmagnesium hydroxide, and combinations thereof. One particular chemicaltreatment that is especially favored in the current wastewatercollection system (sewer lines and lift stations) market involves thefeed of a nitrate salt in order to provide an alternative oxygen sourceto sulfate for the bacteria to metabolize, resulting in the conversionof nitrate into odor-free and corrosion-free nitrogen gas.

Many of these hydrogen sulfide oxidizing or scavenging chemicaltreatments are applied into wastewater that is traveling through thesewer lines out in the collection system prior to reaching thewastewater treatment facility. However, in some cases, these additiveshave been employed at or within the wastewater treatment facility toreduce the formation of H2S at the plant. In particular, these treatmentchemicals can be added within the anaerobic digestion process, insludge, that is present in larger volume wastewater treatment plants.

One of the most widely applied chemicals for the control of H2S inanaerobic digesters is ferric chloride, FeCl3, which is readilyavailable and inexpensive. The ferric cation reacts rapidly withhydrogen sulfide to form a highly insoluble ferric sulfide precipitate.This solid results in the sulfide being trapped within the digestedsludge and, thereby, mitigating the odor.

A significant detriment to the use of ferric chloride within ananaerobic digester is the acidic nature of the product. The commercialform of ferric chloride typically has a pH below 1, which is highlyacidic. The addition of such an acidic product into the digester candestabilize the activity of the anaerobic bacteria. Reduced activity ofthe anaerobic bacteria can result in reduced methane production andlower sludge reduction. In addition, the acidic nature of ferricchloride can cause corrosive damage to metal surfaces that it encounterswithin the digester environment. This is especially important fordigester tanks that have poor sludge mixing and or distribution systemsthat allow the acidic ferric chloride sludge to concentrate in localizedareas within the tank and can result in severe accelerated corrosiondamage. In addition, as a weak acid, H2S exists in equilibrium with theHS- anion according to the following equation:

H2S HS-+H+

As the pH decreases (and the concentration of H+ increases) theequilibrium shifts to favor the H2S species—which is volatile,malodorous, and causes gas-phase corrosion of concrete and metalstructures. Therefore, with the feed of an acidic product, such asferric chloride, into an anaerobic digester, the decreased pH of theanaerobic sludge will shift the equilibrium to favor H2S, and thus anyH2S that did not react directly with the ferric chloride will bevolatilized.

Compounds other than Ferric Chloride are commonly used as well. Forexample, aluminum-containing chemicals are used in the waste watertreatment industry to react with suspended solids within the wastewaterto form flocculated particles that enhance settling and dewatering ofthe sludge. The most common aluminum-containing chemicals that have beenemployed for this purpose are alum (aluminum sulfate), aluminumchloride, polyaluminum chloride, and aluminum chlorohydrate. However,these chemical products, like ferric chloride, are acidic in nature, andcan therefore cause the same detrimental issues as mentioned above(reduced microorganism activity, reduced methane production, increasedcorrosion).

Non-acidic additives have been used in waste water treatment, but arelimited to upstream additions aimed at general improvements in thecoagulation of organic solids within the aerated sections of awastewater treatment process, and improvements in phosphorous removal.For example, sodium aluminate has been added upstream to the primaryflow of wastewater through a treatment plant. For example, as describedin USALCO® “white paper” entitled “Phosphorus Removal in WastewaterTreatment Plants Utilizing USALCO® 38 (liquid sodium aluminate, 38%solid). This process is used in order to effectively remove solubleorthophosphate from the water. The addition of sodium aluminate asdisclosed by USALCO®, has zero reductive effect on the production ofhydrogen sulfide. USALCO® describes adding USALCO® 38 in four possiblelocations, none of which address sludge collected and removed from themain water line, and treated in the anaerobic digester.

The present invention overcomes and improves upon the prior art. Thepresent invention utilizes an alkaline form of an aluminum-containingchemical for a new and novel purpose. For example, according to methodsof the present invention, sodium aluminate (or other variations usingalternative salts) is fed not at the upstream portion, or into theprimary flow at all, and instead into the captured sludge destined forthe anaerobic digester or directly into the anaerobic digester. In bothof these non-limiting examples, utilization of the method taughtaccording to the present invention reduces malodorous hydrogen sulfide.The method and system as taught according the various embodiments, hasadditional benefits, including increased pH, increased anaerobicactivity, increased methane production, increased phosphorous capture inthe sludge, decreased corrosive damage, and decreased struviteproduction.

Accordingly, there is a need in the art for a process that can reducehydrogen sulfide odor, without the negative features present in theprior art.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic depiction of a wastewater treatment process proneto generating high levels of H2S; and

FIG. 2 is a schematic depiction of a wastewater treatment processconfigured to generate reduced levels of H2S.

DETAILED DESCRIPTION

In general terms, compositions and methods of using the alkaline form ofan aluminum-containing chemical are described in the sludge collectionand digestion steps of wastewater processing to effect H2S reduction inthe sludge.

More particularly, various embodiments of the present invention teachsystems, compositions, and methods of applying effective amounts ofalkaline-producing aluminate salts, for example, but not limited to,sodium (Na) and/or potassium (K), into an anaerobic digester for thepurpose of reducing the release of hydrogen sulfide. The reduction ofhydrogen sulfide generation is effected by providing an alternativesource of elemental oxygen, which increases the pH, at differentwastewater processing points via sufficient exposure ofalkaline-producing aluminate salts. This addition may occur with aprimary sludge generated by wastewater treatment processes of incomingraw sewage, secondary sludge generated by partially processed sewage,and/or mixtures of primary sludge and secondary sludge.

Embodiments of the present invention teach the novel use of a solublealuminum ion. For example, an alkaline form of an aluminum-containingchemical may be added to sludge, or an anaerobic digester. Morespecifically, in some embodiments of the present invention, the alkalineform of an aluminum-containing compound may be the combination of analuminate anion, AlO2- and various salts. The most common saltsincorporating the aluminate anion are, for example, but not limited to,sodium aluminate (NaAlO2) and potassium aluminate (KAlO2).

Embodiments of the present invention using aluminate salt to reduce H2Ssimultaneously provide various benefits including, for example:enhancing the coagulation of orthophosphate and other suspended solids,and providing an increase in pH and alkalinity to the digesterenvironment to improve the activity of the bacteria and increase theproduction of methane. Also, by increasing the pH of the digestedsludge, the corrosivity of the overall system is reduced, therebyincreasing the life of system components that would otherwise be eatenaway by corrosive prior art chemical compositions.

The present invention comprises systems and methods for reducing odorand corresponding corrosion related to the production of hydrogensulfide and other volatile organic sulfides within a waste watertreatment facility, or anywhere else where anaerobic digestion oforganic matter results in unwanted levels of hydrogen sulfide and othervolatile organic sulfides. Embodiments of the present invention areunderstood with regards to the figures below.

Disclosed is a method for reducing odor and corresponding corrosion ofhydrogen sulfide and volatile organic sulfides within a wastewateranaerobic digestion process which consists of feeding an alkaline formof aluminum into, or prior to, for example, the anaerobic digester in awastewater treatment facility at various points.

FIG. 1 is a schematic depiction of a typical wastewater treatmentprocess 100 prone to generating high levels of H2S. Process 100commences with receiving incoming raw sewage at block 104 which is thensubjected to a bar screen step at block 108, whereupon the screenedsewage is transferred to a Grit Chamber 116. Thereafter at process block120, a primary settling of settleable solids into a primary sludgeoccurs, wherein an effluent upper layer is directed to an aeration tankat block 124. After sufficient aeration, at process block 128 asecondary settling occurs and a cleaner effluent is routed forchlorination at in the Chlorine Contact Chamber 132. Should the cleanereffluent be deemed not sufficiently cleaned, a portion of the effluentemerging from the secondary settling tank 128 may be rerouted back tothe aeration tank 124 for another aeration exposure. After sufficientchlorination of the cleaner effluents, a releasable-quality effluent isrouted for recycling use at Effluent Delivery block 136, therebycompleting the effluent side of the H2S prone wastewater process 100.

The primary sludge portions created at primary settling block 120 isthen routed to the sludge thickener chamber at process block 140.Similarly, any secondary sludge created at secondary Settling block 128is routed to the sludge thickener chamber 140 for mixing with anyprimary sludge already residing in the sludge thickener chamber 140.Thereafter the sludge is removed from the sludge digester 144 anddelivered to the drying bed 148. After sufficient drying, the high levelH2S containing dried sludge is disposed at block 152, thus completingthe sludge side of the H2S prone wastewater process 100.

FIG. 2 is a schematic depiction of an H2S-reducing wastewater treatmentprocess 200 configured to generate reduced levels of H2S residing withinor emanating from sludge. The receipt of raw sewage to the generation ofreleasable-quality effluent for recycling is the same as the effluentside of process 100 described in FIG. 1. However, in this embodiment ofthe invention, the primary and/or secondary sludges are processeddifferently than the H2S prone process 100.

Referring again to FIG. 2, the sludge processing portion of process 100has been modified to be an H2S-reducing process 202 working in concertwith an alkaline-generating Aluminate Salt process 204. Accordingly, thesludge thickener chamber 140 and the sludge digester 144 of the process100 described in FIG. 1 now receive sufficient quantities ofH2S-reducing Aluminate salts such that each now respectively operate asa Sludge Thickener and H2S-reducing Chamber 214 and an H2S-reducingSludge Digester 218 via receipt of alkaline aluminum containingchemicals from a dispenser 210. In some embodiments, the injection orintroduction of aluminate salt (alone or in addition with otherchemicals) may occur prior to the chamber 214 or digester 218, forexample, in the piping leading to either. In such an embodiment,modification to the chamber 214 and or the digester 218 may not benecessary.

The introduction of aluminate salts from dispenser 210 result in theH2S-reducing process 202 that effects a sufficient reduction of H2Sresiding in and/or emanating from the sludges, either primary and/orsecondary sludges that occupy the sludge thickener and H2S-reducingChamber 214 and the H2S-reducing Sludge Digester 218, by theirrespective exposure to sufficient quantities of pH-raising AluminateSalts received from the Dispenser 210. The alkaline-generating AluminateSalt process 204 includes the dispenser 210 configured to add solidAluminate Salts and/or liquid concentrates of same to the SludgeThickener and H2S-reducing Chamber 214 and the H2S-reducing SludgeDigester 218.

The amount of aluminate salts dispensed is that effective amount deemedsufficient to reduce acidity by increasing the pH to a level thatresults in sufficient reduction of H2S residing within the sludge and/oremanating from the sludge occupying the Sludge Thickener andH2S-reducing Chamber 214 and the H2S-reducing Sludge Digester 218. Theeffective dose will also depend on the concentration of the sludge beingtreated. In some cases, the sludge will contain as little as 0.1% totalsolids (dilute sludge), while in other cases the sludge can contain 10%total solids (concentrated sludge). More commonly, the sludgeconcentration will be in the range of 1% to 5%. For these reasons, theeffective dose of alkaline aluminum-containing product may be as low as0.1 mg into 1.0 L of dilute sludge or as high as 1000 mg into 1.0 L ofconcentrated sludge.

The effective dose may also depend on the goal of the treatment. Forexample, three exemplary primary treatment goals follow, and the dosewill depend on the most important goal of the processing plant. (1)Reduce acidity and/or build alkalinity: this improves microorganismactivity and biogas (methane) production; (2) Reduce hydrogen sulfiderelease: this reduces odor and gas-phase corrosion, and results in acleaner biogas for use as a renewable fuel; (3) Reduce phosphate in theeffluent: this converts the soluble ortho-phosphate ions in the sludgeinto an insoluble aluminum phosphate precipitate that remains with thesludge, resulting in reduced total phosphate in the final effluent.

In various embodiments, dispenser 210 may only operate at one location,for example, at the thickener 214. In such an embodiment, additionalamounts of an alkaline aluminum containing chemical may be necessary atthat single location as compared to an embodiment with multipledispensing points. The aluminum compound will continue to control H2Sproduction within the sludge as the sludge moves from the thickener 214to the digester 218 and beyond, so long as it remains a source ofelemental oxygen. Increasing the amount of aluminum containing compoundwill increase the reduction of H2S, up unit the point where it no longerbecomes effective because the sludge is sufficiently exposed. After thesludge exits the digester 218, the H2S-reduced sludge may be subjectedto a drying process at the Drying Bed 222. Then, at block 226, theH2S-lowered sludge is disposed, thereby completing the H2S-reducingwastewater treatment process 200.

The exact system disclosed in FIG. 2 is only representative of a typicalwaste water treatment facility. In other embodiments, the exactcomponents and order of operations may differ. However, in preferredembodiments, sludge is diverted, and treated, according to the methodsdisclosed herein.

Testing, using a process similar to that depicted in FIG. 2, has shownthat Sodium Aluminate (39%) can achieve a comparable reduction of H2S ascompared to two-times the dose of Ferric Chloride (39%). Morespecifically, in testing, treatment of 400 mL of sludge containing 120mg/L of H2S with a dose of 1 mg/L of SA decreased the H2S to 16 mg/L(87% reduction), while treatment of 400 mL of sludge containing 112 mg/Lof H2S with a dose of 2 mg/L of FC decreased the H2S to 8 mg/L (93%reduction). In addition, the resulting pH changes in each experimentwere as follows: addition of 1 mg/L of SA raised the sludge pH from 5.97to 7.58, resulting in a less corrosive and more biologically activesludge, while the addition of 2 mg/L of FC decreased the sludge pH from5.97 to 4.56, resulting in a more corrosive, and less biologicallyactive sludge.

In accordance with various examples of the invention, for example asdepicted in FIG. 2, an alkaline form of aluminum may be fed into eitherthe Sludge Thickener and H2S-reducing Chamber 214, or, alternatively, orin addition, into the H2S-reducing Sludge Digester 218. In variousembodiments, an alkaline form of aluminum may be fed into the sewagestream just before the Chamber 214 or Digester 218. These locations maybe referred to by various names, and should not be limited by theterminology used herein. In accordance with still further examples ofthe invention, the feed, or dispensing point 210 for the alkaline formof an aluminum-containing chemical may be, for example, either into theinfluent stream that introduces new sludge into the digester 218, orinto the recirculation stream that recirculates the sludge within thedigester 218, or using a split feed into both feed points. In otherembodiments, for example referring back to FIG. 2, the alkaline form ofan aluminum-containing chemical may be added in the stream that leads tothe Thickener 214, or, alternatively, the stream between the Thickener214 and the Sludge Digester 218. The aluminum containing chemical may beadded as a solid, powder, or hydrated liquid at any of the variouspoints disclosed herein. Further, different forms and types of aluminumcontaining chemicals may be used at different points to reduce therelease of hydrogen sulfide by trapping malodorous hydrogen sulfide gasin the sludge.

Further, the mixture dispensed by dispenser 210 may be composed of anynumber of combinations of alkaline aluminum containing salt. Forexample, Sodium Aluminate and Potassium Aluminate, along with variousother impurities that may be present, may be combined and dispended intothe sludge stream at any point disclosed herein. Additionally, differentalkaline aluminum containing compounds or mixtures may be dispensed atdifferent points.

Many variations of the compounds used according to the present inventionare possible. For example, the sodium aluminate embodiment may utilizeany number of variations of the generic compound, including at least,but not limited to: Na2Al2O4, NaAl(OH)4, Na2Al2O3, Na5AlO4, NaAl3O8 orother commercially available variations, all of which are deemed to beencompassed by the general term sodium aluminate. While the exampleabove relates to the sodium aluminate embodiment, the same logic appliesto all other chemical variations and mixtures contemplated by thepresent invention. Further, commercially available versions of thecompounds described herein may also include any number of additionalcompounds. Due to the environment in which the chemicals are introduced,other reactions and intermediaries may occur, and products may differslightly from those specifically described herein, but are consideredwithin the scope of the present invention.

In accordance with yet another example of the invention, the use of oneor more additional alkaline substances, such as magnesium hydroxide,magnesium oxide, calcium hydroxide, calcium oxide, soda ash, sodiumbicarbonate, potash, or ammonia, or blends thereof may be used. Suchadditional alkaline substances may increase the pH and alkalinity of theoverall anaerobic digester environment. These additional alkalinesubstances may be used, for example, in instances where the need forincreased pH and alkalinity is greater than what can be provided throughthe singular feed of sodium aluminate. These additional substances maybe added separately, or, alternatively, at the same time as the primaryaluminum containing chemical. Further, more than one additional alkalinesubstance may be used, and where two or more are used, they may be mixedprior to or at the time of addition into the digester. According tovarious examples, by increasing the pH and alkalinity of the overallanaerobic digester environment, the great majority of the hydrogensulfide will be maintained in the anionic HS-form, which is nonvolatileand water soluble. By maintaining the great majority of sulfide specieswithin the water-phase, odor will be minimized and the opportunity forenhancing the contact time for interaction between the sulfide speciesand the aluminum cations (present from the use of sodium aluminate) willbe maximized.

In some embodiments the alkaline aluminum compound may be hydrated, forexample. The hydrated variation of the compounds taught according to thepresent invention may be used where a liquid application method would bepreferable.

In further embodiments, one or more additional alkaline substances, bynon-limiting example: magnesium hydroxide, magnesium oxide, calciumhydroxide, calcium oxide, soda ash, sodium bicarbonate, potash and orammonia, may be added to the anaerobic digester.

Any number of these additional one or more alkaline substances may beblended into a single chemical mixture with the alkalinealuminum-containing chemical. In other embodiments, the one or moreadditional alkaline substances may be added separately to the anaerobicdigester in conjunction with the alkaline aluminum-containing chemical,or may be added in phases, for example, before, during and after theaddition of the aluminum-containing chemical.

In further embodiments, various additional chemicals may be added to, orat the same time, as the alkaline form of an aluminum containingchemical. These additional chemicals may regulate other conditionswithin the sludge, or act to assist the alkaline form of an aluminumcontaining chemical.

In methods according to an embodiment of the present invention where aalkaline aluminum containing chemical is introduced into the capturedsludge destined for the anaerobic digester, or alternatively, into theanaerobic digester, the process benefits from the chemical's high pH.Commercially available USALCO® 38, for example, has a pH ofapproximately 14 (a 1% solution has pH of 11.5). This has the benefit ofproviding an increase in pH and alkalinity to the digester environment.The increased pH and alkalinity can improve the activity of the bacteriaand increase the production of methane. The increased pH will also shiftthe equilibrium of the H2S such that the majority of the H2S will existin the HS- anion form, which is nonvolatile. Since HS- is nonvolatile,the release of the acidic H2S gaseous molecule is mitigated and bothodor and gas-phase corrosion are reduced. Other embodiments of thepresent invention, including variations of aluminum hydroxide, sodiumaluminate, or potassium aluminate, achieve the same or similar benefitsas those described.

In addition to increasing anaerobic production, the addition of aluminumreduces the buildup of struvite. In many anaerobic digesters ammonia NH3and phosphate PO4 are present in significant amounts. When they comeinto contact with magnesium, they produce a hard, scaling solid callstruvite. The aluminum may bind to phosphorus found within the sludge,reducing the amount of MgNH4PO4 that can form. As a result, thedigester, as well as any lines attached thereto, for mixing and ortransporting sludge are less likely to become clogged by struvite slag.

In accordance with still another example of the invention, the variousgases produced by, for example, the anaerobic digester, may be fedthrough a filtration system which includes an alkaline form of aluminum,for example in a powder or liquid form. The resulting material may thenbe returned to the digester, discarded, or used for other purposes.

In accordance with still further examples of the invention, an alkalineform of aluminum can be added to a digester using an automated system.For example, an automated system may include various sensors and controlmodules in order to control the conditions in the thickener or digester.Sensors may provide information about pH, H2S concentrations, Phosphorusconcentration, temperature, or any other useful metric. Using thisinformation, the controller can compare the sensed values to optimumvalues and add or reduce the addition of aluminum salts as necessary.Further, in more complex systems, the system may sense the need foradditional alkaline substances, such as those described above, inresponse to, for example, a desired increase in pH. In accordance withfurther examples of the invention, an alkaline form of aluminum is addeddirectly to the sludge, either automatically, manually or somecombination of the two.

In accordance with still further examples of the invention, the additionof an alkaline form of aluminum is a component of a larger methanecapture system built into the water treatment process, where theaddition of the alkaline form of aluminum increases methane production,while reducing hydrogen sulfide. As a result, it is easier to isolatethe desired methane byproduct, which can then be stored, transferred orused on site as a means of power generation, for example in a gas-firedgenerator.

In accordance with various examples of the present invention, and asdepicted in the Figs, sludge is separated from the main water line in awater treatment facility, for example at 120 or 128, the sludge isdiverted. The separated sludge may then make its way to an anaerobicdigester 218. In certain alternative embodiments, the sludge may betreated with an alkaline form of aluminum as it is traveling to theanaerobic digester 218. Once the sludge reaches the anaerobic digester218, an alkaline form of aluminum is added. As a result of thisaddition, the amount of H2S reaching the gaseous phase is reduced,thereby reducing the malodor as well as decreasing the corrosive effectsof H2S gas. In addition, the pH of the sludge increases, resulting inincreased aerobic activity, producing more methane gas which may bebeneficially captured. As the global market continues to look for energyalternatives to fossil fuels, there is a growing interest in anaerobicdigestion of human and animal waste. The present invention may increasethe possible harvest yield of methane during the wastewater treatmentprocess. Various methods according to the present invention mayincorporate methane capture components and techniques. For example, themethane may be captured from above the digester as it rises. The methanemay then be separated from any remaining oxygen, for example byseparating components based on their density. This captured methane maythen be further processed, stored, or burned in a gas-fire typegenerator, for example. Many other possibilities exist, and the scope ofthe present invention should not be limited to the limited embodimentsdescribed here.

Further, aluminum ions may bond with phosphorous ions within the sludge,reducing the formation of struvite. In some additional embodiments, thealkaline form of aluminum may be added as one component of a multi-parttreatment process, and may be added continuously to the thickener 214and/or the anaerobic digester 218, or in one or more additionsthroughout the process.

In some embodiments, the chemicals may be introduced using an automatedsystem, which in some embodiments, may respond automatically using anynumber of sensors. For example, in one embodiment of the presentinvention, the chemicals may be introduced when a user requests thesystem feed the chemicals into the sludge. In another embodiment, thesystem may contain a number of sensors which automatically request thatthe chemicals be added. These sensors may, in coordination with thesystem, determine the amount of alkaline form of an aluminum containingchemical that is necessary, and may be able to adjust the dosage toaccommodate the actual environment in the digester. In otherembodiments, one or multiple hoppers may be used to store variouschemicals, as taught by the present invention, to the sludge. Theactuation of these hoppers, such that they add an effective amount ofthe one or more chemicals, may be controlled manually or automatically.

The teachings of the present invention may also be useful in other usecases where H2S and pH control is desired. For example, an alkaline formof aluminum can be added, as a solid, powder, or liquid, to variousother locations where anaerobic digestion is underway, for example, anouthouse, mobile restroom, or farm yard retention pond. In one specificexample , at concentrated animal feeding operations (CAFO), someretention ponds have been converted into anaerobic digesters. Themethods taught herein may be used in order to provide the variousbenefits discussed herein to CAFOs. Further, in some situations, theorganic matter may be removed from a CAFO and dried prior to transport.In some embodiments an alkaline form of aluminum can be added duringthis drying and mixing stage in order to provide the benefits discussedherein.

While the preferred embodiment of the invention has been illustrated anddescribed, as noted above, many changes can be made without departingfrom the spirit and scope of the invention. For example, sodiumaluminate has been described, but many other variations, for example bychanging the salt bonded to the aluminate ion, are possible. And,further, the method has been described with respect to a wastewatertreatment facility, but the teachings herein can be applied elsewhereand are within the scope of the invention. Accordingly, the scope of theinvention is not limited by the disclosure of the preferred embodiment.Instead, the invention should be determined entirely by reference to theclaims that follow.

I claim:
 1. A method of reducing gaseous H2S production from anaerobicwaste water sludge comprising: adding an effective amount of an alkalineform of an aluminum containing chemical to a waste water sludge.
 2. Amethod of claim 1 further comprising where the alkalinealuminum-containing chemical is selected from the group of aluminumhydroxide, sodium aluminate, potassium aluminate, and mixtures thereof.3. A method of claim 2 further comprising where the alkalinealuminum-containing chemical is mixed with at least one other chemical,wherein the at least one other chemical is selected from the group ofsodium hydroxide and potassium hydroxide.
 4. A method of claim 1 furthercomprising where the addition of an effective amount of an alkaline formof an aluminum containing chemical occurs at a feed point, and furtherwherein the feed point is into a influent stream, wherein the influentstream introduces new sludge into an anaerobic digester.
 5. A method ofclaim 1 further comprising where the addition of an effective amount ofan alkaline form of an aluminum containing chemical occurs at a feedpoint, and further wherein the feed point is into a recirculation streamthat recirculates the sludge within an anaerobic digester.
 6. A methodof claim 4 further comprising where there exists at least a second feedpoint for the alkaline form of an aluminum-containing chemical, andwherein the at least second feed point feeds into a recirculation streamthat recirculates the sludge within an anaerobic digester.
 7. A methodof claim 1 further comprising the addition of one or more additionalalkaline substances to the waste water sludge selected from the group ofmagnesium hydroxide, magnesium oxide, calcium hydroxide, calcium oxide,soda ash, sodium bicarbonate, potash and ammonia.
 8. A method of claim 7further comprising where the one or more additional alkaline substancesand the alkaline aluminum containing chemical are blended into a singlechemical mixture.
 9. A system for treating wastewater comprising: Adiverted sludge stream; At least one anaerobic digester, wherein thediverted sludge stream enters the digester as an influent stream; Aneffective amount of an alkaline aluminum containing chemical, At leastone addition point, wherein the effective amount of the alkalinealuminum containing chemical is introduced at the at least one additionpoint, and wherein the at least one addition point is located at a pointselected from a group comprising one or more of the influent stream thatintroduces new sludge into the digester, a recirculation stream, whereinthe recirculation stream recirculates the sludge within the anaerobicdigester, and a split feed comprising both the influent stream and atthe recirculation stream.
 10. A composition for treating anaerobic wastewater sludge comprising: an effective amount of an aluminum additive foradding to the anaerobic sludge having the, wherein the aluminum additiveincludes at least one of aluminum hydroxide, sodium aluminate, potassiumaluminate, and mixtures thereof an effective amount of a hydroxideadditive for adding to the anaerobic sludge, wherein the hydroxideadditive includes at least one of sodium hydroxide and potassiumhydroxide and wherein the effective amounts are combinable to form acomposition comprising an alkaline formula capable of being added to theanaerobic sludge to control at least one of sludge pH, hydrogen sulfiderelease, and phosphate in an effluent stream.